Fuel injection systems for internal combustion engines



FUEL INJECTION SYSTEMS FOR INTERNAL COMBUSTION ENGINES Filed June 4,1968 April 14, 1970 w. P. MANSFIELD 5 Sheets-Sheet 1 wrz/vme WILFRED F!MANSFIELD. *%*2"* 4770mm? APril w. P. MANSFIELD 3,505,984

FUEL INJECTION SYSTEMS FOR INTERNAL COMBUSTION ENGINES Filed June 4,1968 v 5 Sheets-Shet 2 FIG.3.

FUEL INJECTION SYSTEMS FOR INTERNAL COMBUSTION ENGINES Filed June 4.1968 April 14, 1970- w. P. MANSFIELD 5 Sheets-Sheet 5VVV////////////////////// April 14, 1970 w. P. MANSFIELD FUEL INJECTIONSYSTEMS FOR INTERNAL COMBUSTION ENGINES 5 Sheets-Sheet 4.

Filed June 4, 1968 April 14, 1970 w. P. MANSFlELD' 3,505,984

FUEL INJECTION SYSTEMS FOR INTERNAL COMBUSTION ENGINES Filed June 4,1968 I 5 Sheets-:Sheet 5 United States Patent Office 3,505,984 PatentedApr. 14, 1970 3,505,984 FUEL INJECTION SYSTEMS FOR INTERNAL COMBUSTIONENGINES Wilfred Percival Mansfield, Slough, England, assignor to TheBritish Internal Combustion Engine Research Institute Limited, Slough,England, a British company Filed June 4, 1968, Ser. No. 734,442 Claimspriority, application Great Britain, June 5, 1967, 25,879/67 Int. Cl.F02m 41/00 US. Cl. 123-139 11 Claims ABSTRACT OF THE DISCLOSURE A fuelinjection system for a multi-cylinder internal combustion engine inwhich the injector nozzles in the cylinders are fed sequentially by fuelunder pressure to open the nozzle valve in each, by way of a plungeroperating in a bore positioned coaxially within a housing rotatable in acasing, cooperating ports and passages being provided around the axis ofthe rotatable casing and housing controlling the passage of fuel to thenozzles, the plunger being operated by liquid under pressure from astorage accumulator by means of a servopiston also co-axial with thebore in the housing, with said servo-piston being of greater diameterthan that of the bore for the plunger. The pressure fluid is spilled toa source of lower pressure at the completion of injection into eachcylinder.

This invention relates to fuel injection systems for internal combustionengines.

The object of the invention is to eliminate the complicated andexpensive mechanically operated pumping arrangements of the knowndistributor type fuel injection-pump and to substitute a hydraulicallyoperated pump system. Further objects of the invention are to employ theknown type of hydraulic pressure intensifier in a novel manner in adistributor type pump and to make advantageous use of the methods andmeans of controlling the fuel injection operation which are madepossible or facilitated by this system. The application of the knowndistributor type pump has been limited to relatively small engines andanother object of the invention is to remove this limitation so that thedistributor system can be applied to medium and large sizes of engines.A still further object is to eliminate the requirement in hydraulicallyoperated systems of providing a separate injection pump for eachcylinder of the engine.

In the following description these objects are achieved by employing anexternal pump which raises the pressure of the servo-liquid to afraction only of the required injection pressure, and this pressureliquid is stored in an accumulator and then delivered under precisecontrol to actuate a servo piston which has a correspondingly greaterarea than the injection pump plunger operated thereby whereby the fuelto be injected is raised to the required injection pressure.

This arrangement has been selected as the most practical system but itwill be understood by those skilled in the art that the servo-liquidcould be raised to therequired injection pressure by the external pumpso that the servo piston of larger area than the injection pump plungerwould be unnecessary if the supply of servo liquid from the externalpump could be timed to correspond with the requirements for operatingthe injection pump plunger in timed sequence with the cycle ofoperations of the engine so that the accumulator would be unnecessary.

The invention consists in a fuel injection system for an internalcombustion engine having at least two cylinders comprising a source ofliquid under pressure, a liquid pressure operated fuel injection pumpplunger, a housing having a bore in which the plunger works, a source offuel and channel means connecting said source of fuel with said bore,wherein the improvement comprises providing the casing with acylindrical bore within which the housing is rotatable and mounting theplunger and bore oo-axially within the housing, and providingcooperating ports and passages around the axis of the ro tatable casingand housing for the delivery of fuel under pressure sequentially to thefront end of an injector nozzle in each cylinder of the engine to openthe nozzle valve and cause injection of fuel into each cylinder, astorage accumulator means connected to said source of liquid underpressure, a liquid pressure operated servopiston working in a cylinderof larger diameter than said bore and actuating said plunger, andconnected to the storage accumulator means, and spilling means forspilling the pressure fuel from the passages to a zone of lower pressureat the completion of injection into each cylinder.

The invention further consists in a fuel injection system as set forthin the preceding paragraph in which a plunger executes one pumpingstroke per cylinder per cycle of said engine.

The invention still further consists in a fuel injection system as setforth in the preceding paragraph in which after the end of eachinjection, the liquid under pressure which operates a fuel injectionpump is discharged to a zone of lower pressure under the control ofpassages in said housing and casing, which communicate with each otherin timed sequence with the cycle of operation of the engine, and leadsto an adjustable throttle.

The invention still further consists in a fuel injection system as setforth above in which the liquid under pressure that operates the fuelinjection pump is fuel.

The invention still further consists in a fuel injection system as setforth above in which additional passages in said housing are placed incommunication with additional passages in said casing through which, intimed sequence with the cycle of operations with the engine, highpressure fuel from said bore is led to a pipe communicating with eachinjector nozzle mounted in a cylinder of the engine, and is delivered tothe rear end of said nozzle to co-operate in closing the nozzle valveand terminating the injection of fuel into said cylinder, and inmaintaining said nozzle valve closed until injection is required on thenext cycle, and in which means are provided for spilling said highpressure fuel from said passages to a zone of lower pressure prior toinjection on the next cycle.

The invention still further consists in a fuel injection system as setforth above in which means are provided for automatically varying thetiming of injection in accordance with the engine speed, with said meanscomprising a plunger slidable in a bore provided with a groove withincreasing cross-sectional area which constitutes an escape path for aflow of liquid under pressure, a quantity of which is dependent onengine speed, and in which the force exerted by the flow of liquid underpressure is applied to one end of said plunger, and is resisted by theforce of a spring applied to the other end of the plunger, so that, asthe speed increases and the flow of liquid pressure increases, theplunger is moved axially against the force exerted by the spring untilthe crosssectional area of the groove is increased to a value sufficientto discharge the flow of liquid under pressure, and said axial movementin conjunction with helical grooves in the driving or driven shaftcausing angular variation of the driven shaft relative to the drivingshaft.

The accompanying drawings show, by way of example only, embodiments ofthe invention, in which:

FIGURE 1 is a longitudinal section through an injection pump constructedin accordance with the invention;

FIGURE 2 is a cross-section through the pump of FIG- URE 1 in line withthe supply and discharge ports of the servo-cylinder, and including anadjustable throttle valve;

FIGURE 3 is a section on the line II-II of FIGURE 2, showing theadjustable throttle valve;

FIGURE 4 is a section through an improved injector constructed inaccordance with the invention;

FIGURE 5 is a section through an alternative injector constructed inaccordance with the invention;

FIGURE 6 is a cross-section through the pump in line with the speedcontrol valve of an all-speed and torque control governor;

FIGURE 7 is a longitudinal section on the line III-III of FIGURE 6,showing the governor system;

FIGURE 8 is a part longitudinal section showing the governor systempositioned to control the quantity of fuel supplied to the injectionpump during the pump filling period;

FIGURE 9 is an end elevation of the pump for a six cylinder engineviewed from the driven end.

By way of example, FIGURE 1 shows one arrangement of a fuel injectionpump constructed in accordance with the present invention. A cylindricalhousing 1 is mounted for rotation within a non-rotating casing 2 so thatit operates as a rotary valve and is driven from the engine. Axiallyarranged in the housing 1 are a servo-cylinder 3 and a servo-piston 4which actuates an injection pump plunger 5 in its bore 6.

A servo-pump and accumulator of known type may be provided. Theservo-pump normally comprises a single piston operated by a singleeccentric or cam and is driven at engine speed. The size of theaccumulator may be reduced by arranging the servo-pump piston to bedriven by a multi-lift cam having a number of cam lifts. For example,there may be the same number of cam-lifts as there are cylinders in theengine, or any arrangement of cams in conjunction with their drivenspeed, which provides the same number of discharges of servo-liquid fromthe pump to the accumulator as the number of discharges from theaccumulator to the servo-cylinder. Each dis charge from the servo-pumpinto the accumulator may occur at substantially the same time as eachdischarge from the accumulator into the servo-cylinder. In a furtherarrangement, the servo-pump may be provided with one or more pairs ofdiametrically opposed pistons, so that the forces on the driving shaftare substantially balanced, and which are operated by one or moreeccentrics or cams driven from the engine at the speed ratio necessaryto give the timing of the discharges from the servo-pump as set outabove. It will be understood that this timing of the discharges isadvantageous but is not essential for the satisfactory operation of theinjection system.

The servo-liquid may be fuel but if it is desired to operate the engineon a heavy fuel which is unsuitable as a servo-liquid this may be doneby providing separate circuits for the heavy fuel and the servo-liquid.The heavy fuel may be supplied at a suitable pressure by a feed pump tothe inlet valve of the injection pump chamber so that the pipes to eachinjector are charged with heavy fuel, while a light fuel, or specialhydraulic fluid, may be used in that part of the system which operatesthe injection pump plunger.

Whichever arrangement of servo-pump is used it must supply servo-liquidunder pressure to the servo-cylinder 3 through a connection 7a and asupply port 7. The housing 1 is provided with equally spaced ports 8,one for each cylinder of the engine. Servo-liquid under pressure issupplied through the port 8 to the cylinder 3 to force the piston 4 tothe right and actuate the plunger 5. In a twostroke cycle engine, thehousing 1 is rotated at engine speed and in a four-stroke cycle engineat half-engine speed. In this way, the pump plunger 5 is actuated onceper cycle for each cylinder and in timed sequence with the cycle ofoperations of the engine. More than one supply port 7 may be provided ifdesired.

Fuel is supplied under pressure, which is preferably servo-pressure, tothe plunger bore 6 to the right-hand side of plunger 5, through apassage 9 and annular groove 9a in the non-rotating casing 2, radialpassages 10 in the housing 1, and a spring loaded feed valve 11. Whenthe plunger 5 is actuated, as described above, and moves to the right,the fuel is discharged at high pressure through a single radial passage12 which communicates in turn with each of a number of outlets 13, andthere is one outlet for each cylinder of the engine. From the outlet 13a pipe 13a conveys the high pressure fuel to an injector at least one ofwhich is mounted in each cylinder of the engine. The rate of dischargeof fuel to the passage 12 throughout the injection period, can becontrolled to a certain extent by choice of the geometry of the supplyport 7 and ports 8.

Injection is terminated when movement of the plunger 5 to the rightcloses the passage 12 (the position shown) and opens communicationbetween the passage 12 and an annular groove 14 in the plunger 5. Thegroove 14 communicates through passage 15 with another groove 16 in theplunger 5, and at this time the groove 16 is placed in communicationwith a radial passage 17 which communicates with a groove 18 around thehousing 1. In this way fuel from the injector and its associated pipe isspilled to a zone of low pressure, for example, the sump of theservo-pump or other reservoir through passages 19 and 20 in the casing2. To control the rate at which the fuel is spilled, a spring-loadedvalve 21 may be positioned between the passages 19 and 20. The valve 21may be arranged to control both the pressure at which it opens and themaximum area of opening. In FIGURE 1 the pressure exerted by the springupon the ball and the lift of the ball are shown to be independentlyadjustable but this is for experimental purposes and when the requiredvalues have been ascertained, a simple arrangement giving fixed valuesof these features can be employed on all further pumps for a givenapplication.

As soon as the pressure at the end of the bore 6 falls below theservo-pressure, in the manner described later, the feed valve 11 opensso that further fuel is supplied under servo-pressure to the plungerbore 6, as described above, and moves the plunger 5 and servo-piston 4to the left thus displacing servo-fluid from the cylinder 3. To permitthis displacement, the casing 2 is provided with a discharge port 22shown in FIGURE 2, which is arranged to communicate with the ports 8 inthe housing 1 at the required times in the cycle of operations of theengine. The liquid discharged from the port 22 is returned to theservo-pump sump or other reservoir through a simple adjustable throttlesuch as is shown in FIGURE 2. The throttle comprises an H-valve 23operating in a bore 24 and arranged to open and close the port 22.Movement of the H-valve 23 downwards in this figure progressively closesthe port 22 and has the effect of reducing the volume of fuel injectedinto the cylinder of the engine as described below. The movement isresisted by a spring 25 and is caused by a projecting segmental portion26 of a control spindle 27, shown in FIGURE 3, which is turned by acontrol lever 28. The portion 26 limits the spring assisted movement ofthe H-valve 23 upwards. Movement downards is limited by an idling speedadjusting screw 29 loaded by a spring 30 and mounted in a screwed sleeve31 which is slidable in a plug 32 and which is provided with a sealingcap 33. Additional force applied to the lever 28 moves the H-valvefurther downwards against the resistance of the two springs 25 and 30thus closing the port 22 completely and shutting down the engine. Inaddition to being controlled manually, the throttle may be controlled byan engine governor of the maximum speed or all-speed types, or by amaximum area limiting device depending on the type of service for whichan engine is required. Variation of the area of the passageway throughthe throttle determines the volume of liquid that is discharged from thecylinder 3 and thus the length of the return movement to the left inFIGURE 1 of the piston 4. The movement of the plunger is the same andthus determines the volume of fuel that is passed into the bore 6 and isinjected into a cylinder of the engine on the next injection. Thearrangement ensures that the required volume of fuel is present in thebore 6 prior to one of the ports 8 coming into communication with thesupply port 7 to start a new injection. The arrangements used to meterthe volume of fuel and to cause the injection of fuel are the same onall injections, so each cylinder receives the same volume of fuel underthe same conditions. The arrangement also ensures that the maximumreturn movement of the plunger 5 is completed before the passage 12uncovers the next port in the casing 2 leading to the injector ofanother cylinder.

FIGURE 1 shows a preferred arrangement of the servo-system in which theservo-cylinder 3 and servopiston 4 are of larger diameter than the pumpplunger 5 and its bore 6. In this way, the servo pressure required for agiven injection pressure may be reduced or the injection pressure for agiven servo pressure may be increased. This arrangement does not requireany changes in the operation of the system as described above.

In accordance with a further embodiment of the invention, thecylindrical housing 1 is not rotated and a cylindrical rotary valve ismounted between the nonrotating housing 1 and the non-rotating casing 2.The rotary valve is provided with ports which place passages in thehousing 1 as described above into and out of communication with passagesin the casing 2 in timed sequence with the cycle of operations of theengine and as described above.

The servo-liquid pump and the accumulator may be built as a unit withthe fuel injection pump and in any case it is desirable that theaccumulator be adjacent to the fuel injection pump.

The normal types of injectors may be used but in accordance with anotherembodiment of the invention the injection pump described above is usedin conjunction with a special design of injector. In modern enginesthere is often considerable difficulty in arranging suflicient space inthe cylinder head to accommodate the injector. Thus injectors of smalldimensions are coming into use and the present proposals facilitate theemployment of small injectors. The injector shown in FIGURE 4 includes astandard nozzle 40: and cap nut 41, as it is of practical importancethat standard nozzles can be used. In addition to the nozzle, theinjector comprises a body 42 in which are arranged connections 43 and 44and passages 45 and 46. The connection 43 and passage 45 lead to alifting face 47 of a needle valve 48 in the normal manner. Theconnection 44 and passage 46 lead to the rear end of the needle valve48. The normal push rod, spring, spring plates and spring adjustingscrew have been eliminated with a consequent reduction in cost and areduction in the mass of the moving parts. The normal leakage fuelconnection is replaced by the second high pressure connection 44.

Although the injector shown in FIGURE 4 is smaller than the normalinjector it is not as small as is possible with the present system andFIGURE 5 shows an altemative injector of small dimensions. Thiscomprises a body 82 which can be manufactured cheaply from steel tubing,containing a needle valve 83, the pointed end of which seats in a nozzle84 while the other end is located by a close-fitting bush 85 pressedinto the body. When the nozzle 84 is in positiomthe end of the body 82is rolled over. A threaded connector 86 for the pipe communicating witha space 87 at the rear end of the needle valve serves also to limit themovement of the valve, with adjustment being effected by turning theconnector and then securing it in position by means of a lock-nut 88. A

banjo-type connector 89 for the pipe communicating with the front end ofthe valve is shrunk 'on to the body 82.

The operation of these arrangements is described in relation to FIGURE 4and the operation in accordance with FIGURE 5 is the same. Theconnection 43 is connected to a pipe 13a which leads to one of theconnections 13 in the casing 2, shown in FIGURE 1. When the plunger 5 isactuated and discharges fuel under high pressure, as described above,this fuel is delivered through passage 45 to the front end of the needlevalve 48 thus opening the valve and injecting fuel into the cylinder inthe normal manner. Supply of oil to passage 45 is terminated asdescribed earlier, including the spilling of the fuel in the pipe 13a toa zone of low pressure.

The connection 44 is connected to a pipe 49 which leads to one ofconnections 50 in the casing 2. In the same manner as for connections13, described in relation to FIGURE 1, there is a connection 50 for eachcylinder of the engine and thus for each injector. The connection 50communicates in timed sequency with the cycle of operations of theengine with a single radial passage 51 in the housing 1 which leads tothe bore 6. As described earlier, in connection with FIGURE 1, movementof the plunger 5 to the right closes the passage 12 and stops deliveryof fuel through the pipe 13a to the front of the nozzle 48, but themovement of plunger 5 to the right is arranged to continue so that fuelis pumped through a longitudinal passage 52 in the plunger 5 and radialconnecting passage 53 to annular groove 54. When the further movement ofthe plunger 5 places the groove 54 in communication with the radialpassage 51 fuel under high pressure is delivered through the connection50, pipe 49, connection 44 and passage 46 to the rear end of the needlevalve 48. This action is arranged to occur a little earlier than thespilling of the fuel in the pipe 13a leading to the front end of thevalve 48. In this way, the pressure on the front of the valve 48 isfalling back to its residual pressure determined by the spring-loadedvalve 21, while the pressure on the rear end of the valve 48 isincreasing rapidly. The valve 48 is forced to its seat before the pressure at the front thereof has fallen to a low value and the fuel infront of the valve 48 is pumped out at a high pressure so that a highrate of injection is maintained until the end of injection. Shortlyafter this time one of the ports 8 in the housing 1 uncovers thedischarge port 22 in the casing 2 so that the pressure in the bore 6 andalso in the pipe 49 falls and when servo pressure is reached, thespring-loaded feed valve 11 opens and fuel at servo pressure frompassage 9 maintains this pressure while pushing the plunger 5 andservo-piston 4 to the left. The pressure maintained on the rear of thenozzle valve 48 ensures that the nozzle remains closed until the nextinjection occurs.

Thus, all the required changes of pressure at both front and rear of thenozzle needle will have been completed by the time the plunger 5commences its return stroke.

'Rotation of the housing 1 closes the passage 12 as soon as the pipe 13ahas been spilled and a little later closes the passage 51 leading to thepipe 49. This latter action occurs shortly after the discharge port 22is opened. The arrangement also ensures that the maximum required returnmovement of the plunger 5 is completed before the passages 12, 51uncover the next pair of ports in the casing 2 leading to the injectorof another cylinder.

As the servo-piston 4 approaches the end, of its stroke in moving to theright, it pumps out the leakage fuel ahead of it through passage 55,annular groove 56 and passage 57 to a spring-loaded non-return valve 58whence it is returned to the sump of the servo-pump or other reservolr.

In an alternative arrangement, the pipes 49 leading to the rear of thenozzle valve 48 may be unloaded through an adjustable spring-loadedvalve 59 which is similar to the valve 21. In this arrangement, thevalve 59 communicates with annular groove 54 through passage 60, annulargroove 61 and passage 62. This unloading of pipe 49 is arranged to occurvery shortly after it has received the high pressure fuel. The valve 59provides a limited escape passage for fuel during the further movementof plunger and thus forms a dash pot bringing the plunger 5 and piston 4to rest more gradually over a greater distance. As soon as the plunger 5comes to rest, the pipe 49 will commence to unload through the valve 59,so that more time is available for unloading and the action can be moregradual. The opening pressure of the valve 59 will be set somewhat abovethe servo-pressure and when the discharge port 22 is opened, thepressure in the pipe 49 and associated passages will fall to theservo-pressure. In addition, the valve 59 allows fuel to be dischargedfrom the pipe 49 when the needle valve 48 moves to the open position.When the plunger 5 moves to the left to commence even the shortestpumping stroke, the radial passage 51 and passageway 62, 61, 60 leadingto the valve 59 are placed in communication through a wide annulargroove 63 so that when the next pumping stroke begins and the nozzlevalve 48 moves to its open position, some fuel is displaced through thevalve 59. The arrangements whereby the various actions take place moregradually than normal have a beneficial effect in reducing the amplitudeof the waves created by these actions.

The torque required to drive the housing 1 is very light so the systemfacilitates the employment of a simple arrangement for the automaticvariation of injection timing with change of engine speed. For example,a plug 64 is used to close the servo-cylinder 3 and to act as a stop forthe servo-piston 4 at maximum output. This plug is secured by a threadedring 65 and is provided with a bore 66 in which slides a close fittingplunger 67. Head 68 of the plunger 67 is provided with a headed bolt -69which carries two pairs of rollers 70. The outer pair engage in twohelical grooves 71 cut in the side of a bore in a driving shaft 72 andthe inner pair engage in two axial grooves 71a cut in the side of a borein the plug 64. The rollers 70 are retained in position by a washer andsplit pin at the outer end of the headed bolt 69.

Axial movements of the plunger 67 in its bore 66 produce angulardisplacements of the plug 64 and housing 1 relative to the driving shaft72 and thus provide the required advance and retard of the injectiontiming.

To achieve the required axial movements of the plunger 67, the fueldischarged from the valve 21, and if desired also from the valve 59, isled to the right-hand end of the bore 66 via passages 20 and 73, groove74, passage 75, groove 76 and passage 77. The frequency of thedischarges of fuel from the valves 21 and 59 is proportional to theengine speed and by the use of the arrangement described, a flow ofliquid under pressure, the quantity of which is dependent on enginespeed, is produced and the force exerted by this flow of liquid underpressure is applied to the right-hand end of the plunger 67. An escapepath for this fuel from the bore 66 to the sump or other reservoir isprovided by a groove 80 formed in the plunger 67. A spring 78 located ina bore 79 in the driving shaft 72 acts on the other end of the plunger67. The liquid under pressure entering the bore 66 moves the plunger 67to the left against the increasing force of the spring 78 until thepressure in the bore 66 and the area of the groove 80 exposed at theopen end of the bore are, in combination, sufiicient to discharge thespeed-dependent flow of liquid. Any desired variation of injectiontiming with speed is obtained by choice of the spring 78 and selectionof the variation of the cross-sectional area of the groove 80 along itslength. If a further control of this timing variation is required, anadjustable or interchangeable fixed bleed 81 can be provided in thepassage 20.

When the simple throttle shown in FIGURES 2 and 3 is used, the lever 28must be operated to adjust the pump output per stroke to the amountrequired according to the speed and torque required of the engine. Themaximum pump output obtainable is determined by the 8 maximum pumpstroke, which is limited by the position of the inner face of the plug64 in FIGURE 1. The maximum pump output is therefore approximately thesame at all engine speeds.

The valve arrangements shown in FIGURES 6 and 7, provide all-speedgoverning of the engine to which the pump is fitted, and limit themaximum torque of the engine to any desired value at each running speed.These arrangements, like the simple throttle valve shown in FIGURES 2and 3, control the return fiow of servo oil from the discharge port 22.

In FIGURES 6 and 7, the oil leaving the discharge port 22 passes intopassage and hence, via a first throttling orifice 91 controlled by aspeed control valve 92 BIIdLfl second throttling orifice 93 controlledby a torque control valve 94, to a discharge passage 95 and dischargepassage outlet 96 which is connected to the reservoir.

The end of a bore 97 in which the torque control valve slides and theend of a bore 98 in which the speed control valve slides are bothconnected by a passage, such aspassage 99 in FIGURE 6, to a bore 100which is connected by a passage 101 which the groove 74 already referredto in connection with FIGURE 1. By virtue of the actions alreadydescribed, the pressure of the oil in this groove increases withincrease of engine speed. Hence, a speed-dependent pressure acts on oneend of each of the two valves 92 and 94.

The speed control valve 92 is provided with a spring 105, the force ofwhich, in relation to the position of the valve, is adjustable by movinga sleeve 106, e.g. by means of a lever 107 shown in section. Theposition of the sleeve 106 determines the engine speed at which therising pressure at the end of the bore 98 overcomes the force of thespring and moves the valve 92 downwards, reducing the effective area ofthe orifice 91, thus limiting the speed.

In the case of the torque control valve 94, the force produced by thespeed-dependent pressure acting on one end of the valve is opposed bythe force of spring 102 housed partly within the valve and partly withina plug 103 which closes the end of the valve bore. The spring iscompressed increasingly as the engine speed increases. The position ofthe valve, which is shown in the maximum speed position, and hence theeffective fiow area of the orifice 93 are thus dependent on enginespeed. By suitable choice of the shape of surface 104 of the valve, theflow areas available at the orifice 93 at various engine speeds andhence the values of maximum torque obtainable at various engine speedsmay be arranged to suit any particular engine duty, within the limits ofperformance of the engine.

The engine may be made to idle at a selected speed by limiting themovement of the sleeve 106 or lever 107 downwards in FIGURE 7, but ithas been found that steadier idling is obtained by directly limiting themovement of the speed control valve 92 downwards so that a fixed minimumeffective flow area is provided at the orifice 91. A rod 108, which isadjustably supported by a bracket 109 and locked in the adjustedposition by a nut 110, permits a rapid adjustment of the idling speed toa precise value by limiting the movement of the valve 92 downwards.Where ready adjustment is unnecessary, the rod 108, bracket 109 and nut110 may be omitted, with sleeve 106 being replaced by a simple plunger,and the downwards movement of the valve 92 being limited by the innerend of a plug 111, which is suitably dimensioned.

When the speed of the engine has been reduced to idling speed, the valve94 will have moved close to the upper end of the bore 97. To stop theengine, rod 112 is moved upwards, for example, :by means of a lever 113shown in section, thus moving the valve 94 still further upwards so thatthe orifice 93 is completely closed.

Oil which leaks from the passages 90 and 95 past the valves to the endsof the bores containing the springs is drained to the reservoir viapassages 114, 115 and 116 shown in FIGURE 6.

An alternative arrangement is shown in FIGURE 8 in which instead ofcontrolling the output of the pump by throttling the discharge flow fromthe servo cylinder by means of valves 92 and 94, the valve arrangementas shown in FIGURES 6 and 7 is moved through 90 and is placed across thepassage 9, through which fuel at servo-pressure passes from theaccumulator to the pump inlet valve 11. In this manner the inlet flow offuel is throttled and thus the quantity of fuel entering the pump duringthe filling period is controlled. The actions of the speed and torquecontrol valves 92 and 94 in the arrangement are the same as describedabove.

In a case where the servo-piston of a diameter greater than the pumpplunger is used, the flow rate of the fuel to the pump chamber is afraction only of the rate of discharge flow from the servo cylinder. Theeffective areas required at the orifices 91 and 93 will becorrespondingly smaller and the valves themselves and the passages maybe made smaller if desired.

I claim:

1. In a fuel injection system for a multi-cylinder internal combustionengine of the type comprising a fuel injector for each cylinder and anozzle valve for each injector, a source of liquid under pressure, acasing, a housing supported within the casing, a pump having a liquidpressure operated plunger working in a bore in said housing, a supply offuel unler pressure, channel means conveying said fuel to said pumpbore, and a distribuitor controlling the passages of fuel from said borecyclically to said injectors, the improvement comprising providing saidcasing with a cylindrical bore within which said housing is rotatable,the pump plunger at its bore being positioned co-axially within saidhousing, flow control means in the channel means for the supply of fuelto said pump bore, said housing having ports and passages, said casinghaving passages and said pump plunger having interconnected co-axialgrooves which co-operate respectively with the ports and passages in thehousing for delivery of fuel sequentially by way of the passages in thecasing to said injectors, and for the sequential spilling of said fuelfrom said passages to a zone of lower pressure at the completion ofinjection into each cylinder.

2. The fuel injection system as claimed in claim 1 in which means areprovided for controlling the rate of pressure fall and the value of theresidual pressure during the spilling of fuel from the passages leadingto the front of the injector nozzle valve.

3. The fuel injection system as claimed in claim 2 in which means areprovided for controlling the rate of pressure fall and the value ofresidual pressure during the spilling of fuel from the passages leadingto the back of the injector nozzle valve.

4. The fuel injection system as claimed in claim 1 including a cylinder,a pressure liquid operated servo-piston working in said cylinder, saidcylinder being larger than said bore for actuating said pump plunger toeffect injection, storage accumulator means, the cylinder of saidservo-piston being connected to the source of liquid under pressure bysaid storage accumulator means, an adjustable throttle, and means forcontrolling in timed sequence with the cycle of operations of the enginethe flow of liquid under pressure from said accumulator to the cylinderof said servo-piston to actuate said pump plunger to effect eachinjection, and after each injection, the discharge of liquid from saidcylinder to a zone of low pressure through the adjustable throttle.

5. The fuel injector system as claimed in claim 4 in which theservo-piston works in a cylinder co-axial of the pump plunger and Withinthe housing.

6. The fuel injection system as claimed in claim 1 having furtherco-axial grooves and a passage in the pump plunger which groovesco-operate with ports and passages in the housing for controlleddelivery of fuel under high pressure by way of passages in the casing tothe rear end of each nozzle valve to assist to closing said valve andfor the sequential spilling of said fuel from said passages to a zone oflower pressure at the completion of injection into each said cylinder.

7. The fuel injection system as claimed in claim 6 in which thecontrolled delivery of fuel to the front and rear of each nozzle valveis effected by and during the stroke of the pump plunger in such amanner that when the stroke of the plunger has completed the delivery offuel under pressure to the front of the respective nozzle valve,continued movement of the pump plunger delivers fuel under pressure tothe rear end of the nozzle valve.

8. The fuel injection system as claimed in claim 1 including means forautomatically varying the timing of injection in accordance with theengine speed, said means comprising a plunger slidable in a bore andprovided with a groove with increasing cross-sectional area whichconstitutes an escape path for a flow of liquid under pressure, thequantity of which is dependent on engine speed, and the force exerted bythe flow of liquid under pressure being applied to one end of saidplunger, a spring applied tothe other end of the plunger for resistingsuch force, so that, as the speed increases and the flow of liquidpressure increases, the plunger is moved axially against the forceexerted by the spring until the cross-sectional area of the groove isincreased to a value sufiicient to discharge the fiow of liquid underpressure, and said axial movement in conjunction with helical grooves ina driving or driven shaft causing angular variation of the driven shaftrelative to the driving shaft.

9. The fuel injection system as claimed in claim 8 in which theadjustable throttle is an H-valve operated by a lever.

10. The fuel injection system as claimed in claim 8 in which twoadjustable throttle valves are controlled by means providing all-speedgoverning and also torquespeed control.

11. The fuel injection system as claimed in claim 10 in which twoadjustable throttle valves are controlled by all-speed governing andtorque-speed control means which operate in accordance with the pressureof the liquid, with said pressure being dependent upon the speed of theengine and applied to one operative face of each said valve, relative toa spring force applied to the other operative face of said valve.

References Cited UNITED STATES PATENTS 2,291,939 8/1942 Amery 123l 39.112,803,234 8/1957 Mansfield l23l39 2,816,533 12/ 1957 Reggio 123l39.93,058,425 10/ 1962 Evans.

LAURENCE M. GOODRIDGE, Primary Examiner US. Cl. X.R. 1035

